One of these is a subscription service and the other is model weights with a paid API in front of it. Every comparison gets that much right. What most skip decides projects: what each vendor publishes about price, prompting, ownership and automation.
Everything below comes from Midjourney documentation, Midjourney terms and Stability AI pages. Where a number is unpublished, the text says so.
Two delivery models for the same job
Midjourney has no free tier. The plan chart lists four subscriptions, and the service itself is the only interface — Discord, or midjourney.com. You cannot download the model, run it offline, or hold a copy.
Stable Diffusion ships as weights. Stability AI lists four routes: a self-hosted licence, the Stability AI API, cloud partners, and the Stable Assistant app. There is no Midjourney API to compare against. Service versus artifact is the difference that produces all the others.
What Midjourney publishes about itself
The plan chart gives four tiers at $10, $30, $60 and $120 a month, measured in Fast GPU time: 3.3 hours, 15, 30 and 60. Extra time costs $4 an hour, and Stealth Mode starts at Pro. The Midjourney pricing guide turns those hours into job counts.
Ownership is stated plainly: “You own all Assets You create with the Services to the fullest extent possible under applicable law.” Two exceptions follow: a company making more than $1,000,000 USD a year must be on Pro or Mega to own its assets, and upscaling another person’s images does not transfer ownership.
Privacy is a plan feature too: by default your work is public and remixable, and Stealth Mode is a best-efforts commitment rather than a guarantee.
What Stability AI publishes
The models ship under the Stability AI Community License, described on the licence page as “for researchers, developers, small businesses, and creators with less than $1M in annual revenue”, and it is free at that tier. Above $1M in annual revenue the vendor’s answer is an Enterprise licence with “Custom Pricing”.
The FAQ answers self-hosting directly: “Use of the Core Models (including Stable Diffusion 3 2B) is free for everyone, unless you’re using the Core Models for a commercial purpose and you or your organization generate over USD $1M”. Output ownership gets a line too: “you own outputs generated from the Core Models or Derivative Works (such as fine-tunes)”.
The hosted route is metered in credits, and the page gives the unit: “1 credit = $0.01”. Stable Diffusion 3.5 Large costs 6.5 credits per image, Stable Image Ultra 8, Stable Image Core 3. New accounts start with 25 free credits.
The comparison, line by line
| Question | Midjourney | Stable Diffusion |
|---|---|---|
| Where it runs | The vendor cloud only | Your GPU, a cloud partner, or the vendor API |
| Cost of entry | Four subscriptions, no free tier | Free below the revenue threshold, credits above |
| How limits are set | Inline flags, --ar, --no, --stylize | Separate fields, aspect_ratio, negative_prompt |
| Model selection | The --v version flag | The model field, sd3.5-large by default |
| Repeating a render | --seed, on the parameter list | seed, documented from 0 to 4294967294 |
| Owning the output | Yours, with a revenue condition | Yours, with a revenue condition |
| Automation | Prohibited by the terms | The API is a product line |
| Private by default | No, assets are public and remixable | A local run stays local |
Example: one prompt in both tools
Both cases use the same words; only the controls differ.
Example one: a concert poster
Midjourney keeps everything in one line, flags included.
a risograph poster for a night market, bold sans-serif headline reading NIGHT MARKET, two ink colours on cream paper, visible paper grain --ar 2:3 --stylize 250 --v 8.2The Stability sd3 endpoint takes the same words as one field and the controls as siblings of it: prompt, an aspect_ratio defaulting to 1:1, a model defaulting to sd3.5-large, and cfg_scale between 1 and 10.
prompt: a risograph poster for a night market, bold sans-serif headline reading NIGHT MARKET, two ink colours on cream paper, visible paper grain
aspect_ratio: 2:3
model: sd3.5-large
cfg_scale: 4Nothing is lost, and nothing is portable either: the Midjourney line is a string you paste into Discord, and the Stability request is a multipart form a client library fills in.
Example two: a product shot
Negatives are the clearest split. Midjourney folds them into the prompt with --no, which the parameter list describes as telling Midjourney “what you don’t want in your image”.
a single aluminium can on a seamless pale grey background, studio softbox from the left, sharp product photography --ar 1:1 --no text, watermark, hands --seed 4310The Stability side has a field for it: negative_prompt, documented on all three Stable Image generate endpoints, alongside seed.
prompt: a single aluminium can on a seamless pale grey background, studio softbox from the left, sharp product photography
negative_prompt: text, watermark, hands
aspect_ratio: 1:1
seed: 4310
output_format: pngThe consequence shows up in version control: a Midjourney prompt is one reviewable line, while the Stability version is named values that are easier to diff. The style reference guide covers the Midjourney field with no equivalent here.
Cost, licence and ownership
The two do not sell comparable units. Midjourney sells time on GPUs, so an idle month still costs $10 and a heavy month costs the same until you buy hours at $4. Stability charges per image through the API, or nothing if you run the weights yourself. The API page warns that “Pricing is subject to change as we improve our models and infrastructure.”
Both vendors attach a revenue condition to ownership, with nearly the same threshold: $1,000,000 USD a year for Midjourney, $1M for the Stability AI Community License. Below the line the output is yours; above it, the plan or the licence changes.
What neither side publishes
- A quality or uptime commitment. Midjourney states that “No guarantees are made with respect to the Services’ quality, stability, uptime or reliability”.
- A model release schedule for either family.
- Midjourney’s Relax queue priority per tier, or a figure for how many images one credit buys across every Stability endpoint.
- A neutral benchmark run by either vendor.
Frequently asked questions
Can I run Midjourney locally? No. There is no downloadable model and no self-hosted licence. The quick-start guide covers the only route.
Is Stable Diffusion free? The weights are free under the Community License below $1M in annual revenue; the hosted API is metered in credits at 1 credit per $0.01.
Which one can I automate? Only Stable Diffusion. Midjourney’s terms prohibit automated tools, and no API is documented.
Do I own the output either way? Both vendors say you do, each with a revenue condition, and neither promises what a court will recognise.